Ultrafast Time-of-Flight Method of Gasoline Contamination Detection Down to ppm Levels by Means of Terahertz Time-Domain Spectroscopy

Abstract

In this article, we present the possibility of using terahertz time-domain spectroscopy to detect trace, ppm-level (%wt.) concentrations of admixtures in 95-octane lead-free gasoline in straightforward time-of-flight (pulse-delay) measurements performed directly in the liquid. The method was tested on samples containing 75–0.0125% of isopropanol and 0.3–0.0250% of water. The detection limits for isopropanol and water content were determined to be 125 ppm and 250 ppm, respectively, approaching the limits of much more complicated and time-consuming methods (like spectroscopy of the vapor phase). The measured pulse delays were compared with theoretical calculations using the modified Gladstone-Dale mixing rule for the solutions. The comparison demonstrated good agreement for gasoline-alcohol mixtures and large discrepancies for gasoline-water mixtures, suggesting that gasoline-water mixtures cannot be considered idealized binary mixtures. Our results clearly show that the pulse time delay measurement by THz-TDS is a fast and sensitive method of gasoline contamination detection and, as such, can be easily integrated with industrial online real-time quality control applications.

Correction: Stelmaszczyk et al. Ultrafast Time-of-Flight Method of Gasoline Contamination Detection Down to ppm Levels by Means of Terahertz Time-Domain Spectroscopy. Appl. Sci. 2022, 12, 1629

“…The authors wish to make the following corrections to their paper [1]. In the original publication, there was a mistake in Figures 1 and 6c as published.…”

Powerful Elliptically Polarized Terahertz Radiation from Oscillating-Laser-Driven Discharge Surface Currents

“…Radiation of the THz range possesses unique properties for fundamental material studies and high-end applications in medicine, chemistry, and communication [1][2][3][4]. The non-ionizing nature of the interaction makes possible non-destructive ultra-sensitive contamination [5] and chemical compound detection by terahertz spectroscopy [6,7]. In biology, with this kind of radiation, the spectroscopy of biomolecules [8], chemical imaging [9], and even the monitoring of bio-samples' content [10] become feasible.…”